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Use double-checked locking to avoid locking the Module mutex if we don't need to. This avoid a deadlock we were seeing in Xcode. 

<rdar://problem/21512067>

llvm-svn: 243180
This commit is contained in:
Greg Clayton 2015-07-24 23:38:01 +00:00
parent be16d22f04
commit 88c05f54a0
2 changed files with 80 additions and 67 deletions
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11
lldb/include/lldb/Core/Module.h
View File

@ -10,6 +10,7 @@
#ifndef liblldb_Module_h_
#define liblldb_Module_h_
#include <atomic>
#include "lldb/lldb-forward.h"
#include "lldb/Core/ArchSpec.h"
#include "lldb/Core/UUID.h"
@ -1119,13 +1120,13 @@ protected:
PathMappingList m_source_mappings; ///< Module specific source remappings for when you have debug info for a module that doesn't match where the sources currently are
lldb::SectionListUP m_sections_ap; ///< Unified section list for module that is used by the ObjectFile and and ObjectFile instances for the debug info
bool m_did_load_objfile:1,
m_did_load_symbol_vendor:1,
m_did_parse_uuid:1,
m_did_init_ast:1;
std::atomic<bool> m_did_load_objfile;
std::atomic<bool> m_did_load_symbol_vendor;
std::atomic<bool> m_did_parse_uuid;
std::atomic<bool> m_did_init_ast;
mutable bool m_file_has_changed:1,
m_first_file_changed_log:1; /// See if the module was modified after it was initially opened.
//------------------------------------------------------------------
/// Resolve a file or load virtual address.
///

136
lldb/source/Core/Module.cpp
View File

@ -399,15 +399,18 @@ Module::GetMemoryObjectFile (const lldb::ProcessSP &process_sp, lldb::addr_t hea
const lldb_private::UUID&
Module::GetUUID()
{
Mutex::Locker locker (m_mutex);
if (m_did_parse_uuid == false)
if (m_did_parse_uuid.load() == false)
{
ObjectFile * obj_file = GetObjectFile ();
if (obj_file != NULL)
Mutex::Locker locker (m_mutex);
if (m_did_parse_uuid.load() == false)
{
obj_file->GetUUID(&m_uuid);
m_did_parse_uuid = true;
ObjectFile * obj_file = GetObjectFile ();
if (obj_file != NULL)
{
obj_file->GetUUID(&m_uuid);
m_did_parse_uuid = true;
}
}
}
return m_uuid;
@ -416,32 +419,35 @@ Module::GetUUID()
ClangASTContext &
Module::GetClangASTContext ()
{
Mutex::Locker locker (m_mutex);
if (m_did_init_ast == false)
if (m_did_init_ast.load() == false)
{
ObjectFile * objfile = GetObjectFile();
ArchSpec object_arch;
if (objfile && objfile->GetArchitecture(object_arch))
Mutex::Locker locker (m_mutex);
if (m_did_init_ast.load() == false)
{
m_did_init_ast = true;
// LLVM wants this to be set to iOS or MacOSX; if we're working on
// a bare-boards type image, change the triple for llvm's benefit.
if (object_arch.GetTriple().getVendor() == llvm::Triple::Apple
&& object_arch.GetTriple().getOS() == llvm::Triple::UnknownOS)
ObjectFile * objfile = GetObjectFile();
ArchSpec object_arch;
if (objfile && objfile->GetArchitecture(object_arch))
{
if (object_arch.GetTriple().getArch() == llvm::Triple::arm ||
object_arch.GetTriple().getArch() == llvm::Triple::aarch64 ||
object_arch.GetTriple().getArch() == llvm::Triple::thumb)
m_did_init_ast = true;
// LLVM wants this to be set to iOS or MacOSX; if we're working on
// a bare-boards type image, change the triple for llvm's benefit.
if (object_arch.GetTriple().getVendor() == llvm::Triple::Apple
&& object_arch.GetTriple().getOS() == llvm::Triple::UnknownOS)
{
object_arch.GetTriple().setOS(llvm::Triple::IOS);
}
else
{
object_arch.GetTriple().setOS(llvm::Triple::MacOSX);
if (object_arch.GetTriple().getArch() == llvm::Triple::arm ||
object_arch.GetTriple().getArch() == llvm::Triple::aarch64 ||
object_arch.GetTriple().getArch() == llvm::Triple::thumb)
{
object_arch.GetTriple().setOS(llvm::Triple::IOS);
}
else
{
object_arch.GetTriple().setOS(llvm::Triple::MacOSX);
}
}
m_ast->SetArchitecture (object_arch);
}
m_ast->SetArchitecture (object_arch);
}
}
return *m_ast;
@ -1039,15 +1045,18 @@ Module::FindTypes (const SymbolContext& sc,
SymbolVendor*
Module::GetSymbolVendor (bool can_create, lldb_private::Stream *feedback_strm)
{
Mutex::Locker locker (m_mutex);
if (m_did_load_symbol_vendor == false && can_create)
if (m_did_load_symbol_vendor.load() == false)
{
ObjectFile *obj_file = GetObjectFile ();
if (obj_file != NULL)
Mutex::Locker locker (m_mutex);
if (m_did_load_symbol_vendor.load() == false && can_create)
{
Timer scoped_timer(__PRETTY_FUNCTION__, __PRETTY_FUNCTION__);
m_symfile_ap.reset(SymbolVendor::FindPlugin(shared_from_this(), feedback_strm));
m_did_load_symbol_vendor = true;
ObjectFile *obj_file = GetObjectFile ();
if (obj_file != NULL)
{
Timer scoped_timer(__PRETTY_FUNCTION__, __PRETTY_FUNCTION__);
m_symfile_ap.reset(SymbolVendor::FindPlugin(shared_from_this(), feedback_strm));
m_did_load_symbol_vendor = true;
}
}
}
return m_symfile_ap.get();
@ -1288,37 +1297,40 @@ Module::GetObjectName() const
ObjectFile *
Module::GetObjectFile()
{
Mutex::Locker locker (m_mutex);
if (m_did_load_objfile == false)
if (m_did_load_objfile.load() == false)
{
Timer scoped_timer(__PRETTY_FUNCTION__,
"Module::GetObjectFile () module = %s", GetFileSpec().GetFilename().AsCString(""));
DataBufferSP data_sp;
lldb::offset_t data_offset = 0;
const lldb::offset_t file_size = m_file.GetByteSize();
if (file_size > m_object_offset)
Mutex::Locker locker (m_mutex);
if (m_did_load_objfile.load() == false)
{
m_did_load_objfile = true;
m_objfile_sp = ObjectFile::FindPlugin (shared_from_this(),
&m_file,
m_object_offset,
file_size - m_object_offset,
data_sp,
data_offset);
if (m_objfile_sp)
Timer scoped_timer(__PRETTY_FUNCTION__,
"Module::GetObjectFile () module = %s", GetFileSpec().GetFilename().AsCString(""));
DataBufferSP data_sp;
lldb::offset_t data_offset = 0;
const lldb::offset_t file_size = m_file.GetByteSize();
if (file_size > m_object_offset)
{
// Once we get the object file, update our module with the object file's
// architecture since it might differ in vendor/os if some parts were
// unknown. But since the matching arch might already be more specific
// than the generic COFF architecture, only merge in those values that
// overwrite unspecified unknown values.
ArchSpec new_arch;
m_objfile_sp->GetArchitecture(new_arch);
m_arch.MergeFrom(new_arch);
}
else
{
ReportError ("failed to load objfile for %s", GetFileSpec().GetPath().c_str());
m_did_load_objfile = true;
m_objfile_sp = ObjectFile::FindPlugin (shared_from_this(),
&m_file,
m_object_offset,
file_size - m_object_offset,
data_sp,
data_offset);
if (m_objfile_sp)
{
// Once we get the object file, update our module with the object file's
// architecture since it might differ in vendor/os if some parts were
// unknown. But since the matching arch might already be more specific
// than the generic COFF architecture, only merge in those values that
// overwrite unspecified unknown values.
ArchSpec new_arch;
m_objfile_sp->GetArchitecture(new_arch);
m_arch.MergeFrom(new_arch);
}
else
{
ReportError ("failed to load objfile for %s", GetFileSpec().GetPath().c_str());
}
}
}
}